Virtual-network computing is a no-fuss way to remotely view and interact with any computer. RemoteVNC provides secure log-on data encryption so that you can access your main machine even when on the road—and it's simple-to-use interface works between different operating systems, so you can use a notebook running Mac OSX to access a home machine running Windows 7 or Vista. (Unix is also supported.) Both Personal and Enterprise editions are available; customers who choose the latter also have access to the Viewer application for both Android and iOS, which lets users interact with their computer via certain handheld devices. For further simplicity, RealVNC offers a Java viewer so that remote control can take place from within a browser—which means no software installation is necessary on the secondary computer.
COST: Some free versions available; from $30 for paid versions at Realvnc.com.